Chloro Compounds Research Articles

Preparation of Diazoalkane Complexes of Ruthenium and Their Cyclization Reactions with Alkenes and Alkynes

The diazoalkane complexes [Ru(η5-C5H5)(N2CAr1Ar2)(PPh3)(L)]BPh4 (1–5: Ar1 = Ar2 = Ph (a), Ar1 = Ph and Ar2 = p-tolyl (b), Ar1Ar2 = C12H8 (c), Ar1 = Ph and Ar2 = PhCO (d); L = PPh3 (1), P(OMe)3 (2), P(OEt)3 (3), PPh(OEt)2 (4), ButNC (5)) were prepared by allowing the chloro compounds RuCl(η5-C5H5)(PPh3)(L) to react with the diazoalkanes Ar1Ar2CN2 in ethanol. Treatment of complexes 1–5 with ethylene (CH2═CH2) under mild conditions (1 atm, room temperature) led not only to the η2-ethylene complexes [Ru(η5-C5H5)(η2-CH2═CH2)(PPh3)(L)]BPh4 (10–14) but also to dipolar (3 + 2) cycloaddition, affording the 4,5-dihydro-3H-pyrazole derivatives [Ru(η5-C5H5){η1-N═NC(Ar1Ar2)CH2CH2}(PPh3)(L)]BPh4 (6–9). Acrylonitrile (CH2═C(H)CN) reacted with diazoalkane complexes 2 and 3 to give the 1H-pyrazoline derivatives [Ru(η5-C5H5){η1-N═C(CN)CH2C(Ar1Ar2)NH}(PPh3)(L)]BPh4 (19, 20). However, reactions with propylene (CH2═C(H)CH3), maleic anhydride (ma, CH═CHCO(O)CO) and dimethyl maleate (dmm, CH3OCOCH═CHOCOCH3) led to the η2-alkene complexes [Ru(η5-C5H5)(η2-R1CH═CHR2)(PPh3)(L)]BPh4 (17–22). Treatment of the diazoalkane complexes 1 and 2 with acetylene CH≡CH under mild conditions (1 atm, room temperature) led to dipolar cycloaddition, affording the 3H-pyrazole complexes [Ru(η5-C5H5){η1-N═NC(Ar1Ar2)CH═CH}(PPh3){P(OMe)3}]BPh4 (24), whereas reactions with the terminal alkynes PhC≡CH and ButC≡CH gave the vinylidene derivatives [Ru(η5-C5H5){═C═C(H)R}(PPh3){P(OMe)3}]BPh4 (25, 26). The alkyl propiolates HC≡CCOOR1 (R1 = Me, Et) also reacted with complexes 2 to give the 3H-pyrazole complexes [Ru(η5-C5H5){η1-N═NC(Ar1Ar2)C(COOR1)═CH}(PPh3){P(OMe)3}]BPh4 (27, 28). The complexes were characterized by spectroscopy and by X-ray crystal structure determinations of [Ru(η5-C5H5){η1-N═C(CN)CH2C(Ph)(p-tolyl)NH}(PPh3){P(OMe)3}]BPh4 (19b), [Ru(η5-C5H5){η2-CH═CHCO(O)CO}(PPh3){P(OMe)3}]BPh4 (21), and [Ru(η5-C5H5){η1-N═NC(C12H8)CH═CH}(PPh3){P(OMe)3}]BPh4 (24c).

Synthetic and structural studies of piperidine carboxamide uranyl ion complexes

New piperidine based ligands of the type [C5H10NCONR2] (where R=CH3 (L1), C2H5 (L2) and iC3H7 (L3)) have been prepared and characterized. The complex chemistry of these ligands with uranyl chloride, bromide, nitrate and β-diketonates has been studied using IR and NMR spectroscopic methods. Crystal structures for the complexes [UO2Cl2(L3)2] (1), [UO2Br2(L3)2] (2) [UO2(NO3)2(L3)2] (5) and [UO2(C4H3SCOCHCOCF3)2(L3)] (8) have been determined by the X-ray diffraction method. The structures of 1 and 2 show that the uranyl ion is surrounded by two of the ligands and two halogen atoms in an octahedral geometry. The structure of 5 shows that the uranyl group is surrounded by two nitrate groups and two ligands in a hexagonal bipyramidal geometry. The structure of 8 shows that the uranyl group is surrounded by two β-diketonates and one ligand in a pentagonal bipyramidal geometry. The structures show that the carboxamide ligands are strongly bonded to the uranyl group, showing a near linear geometry for the U–O–C bond (angle 150–159°). The prepared chloro and bromo compounds are air and moisture stable and show good solubility in normal organic solvents.

Preparation and reactivity of germyl complexes of ruthenium and osmium stabilised by cyclopentadienyl, indenyl and tris(pyrazolyl)borate fragments

Half-sandwich trichlorogermyl complexes Ru(GeCl3)(η5-C5H5)(PPh3)L (1) and Ru(GeCl3)(η5-C9H7)(PPh3)L (2) [L = P(OMe)3 (a), P(OEt)3 (b) and PPh(OEt)2 (c)] were prepared by allowing chloro compounds RuCl(η5-C5H5)(PPh3)L and RuCl(η5-C9H7)(PPh3)L to react with an excess of GeCl2·dioxane in ethanol. Treatment of trichlorogermyl complexes 1 and 2 with LiAlH4 in THF yielded trihydridogermyl derivatives Ru(GeH3)(η5-C5H5)(PPh3)L (3) and Ru(GeH3)(η5-C9H7)(PPh3)L (4). Instead, reaction of trichlorogermyl complexes 1 and 2 with NaBH4 in ethanol afforded triethoxygermyl complexes Ru[Ge(OEt)3](η5-C5H5)(PPh3)L (5) and Ru[Ge(OEt)3](η5-C9H7)(PPh3)L (6). Trichlorogermyl complexes with the tris(pyrazolyl)borate ligand M(GeCl3)(Tp)(PPh3)L [M = Ru (7), Os (10)] were prepared by reacting chloro compounds MCl(Tp)(PPh3)L with an excess of GeCl2·dioxane. Depending on metal centre, nature of phosphite and experimental conditions, the reaction of trichlorogermyl complexes 7 and 10 with LiAlH4 or NaBH4 afforded trihydridogermyl M(GeH3)(Tp)(PPh3)L (8, 12) and triethoxygermyl derivatives M[Ge(OEt)3](Tp)(PPh3)L (9, 11). The complexes were characterised by IR and multinuclear NMR spectroscopy and by X-ray crystal structure determination of 3a.

Preparation and Reactivity of Stannyl Complexes of Ruthenium(II) Stabilized by an Indenyl Ligand

Trichlorostannyl complexes Ru(SnCl3)(η5-C9H7)(PPh3)L (1; L = P(OMe)3, P(OEt)3) were prepared by allowing chloro compounds RuCl(η5-C9H7)(PPh3)L to react with SnCl2·2H2O in ethanol. Treatment of compounds 1 with NaBH4 in ethanol yielded the tin trihydride derivatives Ru(SnH3)(η5-C9H7)(PPh3)L (2). The reaction of trichlorostannyl complexes 1 with MgBrMe in diethyl ether afforded the chlorodimethylstannyl derivatives Ru(SnClMe2)(η5-C9H7)(PPh3)L (3), whereas reaction with Li+C≡CPh– in THF yielded the trialkynylstannyl compounds Ru[Sn(C≡CPh)3](η5-C9H7)(PPh3)L (4). Treatment of the trihydridostannyl complexes 2 with the alkyl propiolate HC≡CCOOR led to the trivinylstannyl derivatives Ru[Sn{C(COOR)═CH2}3](η5-C9H7)(PPh3)L (5, 6; R = Me, Et). However, the reaction of [Ru]–SnH3 (2) with the propargylic alcohol HC≡CCPh2OH yielded the alkene H2C═C(H)CPh2OH and the hydride RuH(η5-C9H7)(PPh3)L (7). Treatment of tin trihydride complexes 2 with H2O led to the trihydroxostannyl derivatives Ru[Sn(OH)3](η5-C9H7)(PPh3)L (8). ...

Metastable Zone Widths, Conformational Multiplicity, and Seeding

The propensity for crystallisation of acetanilides and propionanilides was compared both by polythermal metastable zone width measurements and by isothermal induction time measurements. Although there were clear relationships between the metastable zone widths and the conformational multiplicity in some cases, they broke down for the chloroacylanilides. This failure could not be fully accounted for by the difference in the crystal structures of the chloro compounds. A surprising dependence of crystal size on seeding effectiveness could explain some of the crystallisation behaviour, particularly for the induction period measurements.

Single-site bismuth alkoxide catalysts for the ring-opening polymerization of lactide

Salen bismuth alkoxides, where the salen ligand contains 2,4-di-tert-butylphenoxy groups and one of ethylene, cyclohexane or ortho-phenyl as a backbone have been prepared from reactions involving Bi[N(SiMe₃)₂]₃ and the free salen ligand followed by alcoholysis (ButOH, PriOH and 2,6-But₂C₆H₃OH). The molecular structures of the salen ligand with the cyclohexyl back-bone have been determined for the complexes salenBiCl and salenBiOC₆H₃-2,6-But₂. The chloro compound is a dimer with chloride bridges while the phenoxide is monomeric with an unusually distorted five-coordinate geometry. The phenoxide and tert-butoxide complexes have been employed in the ring-opening polymerization of lactides (L- and rac-) to give polylactides, PLAs. With rac-LA heterotactic PLA is formed preferentially, Pr = ~0.9, in dichloromethane or toluene at room temperature. The reaction is first order in [Bi] and is notably faster than most aluminum and zinc initiators as well as tin(II) octanoate. These results are discussed in terms of a recent report on the polymerization of LA by Peptobismol® and bismuth subsalicylate.

(NHCMe)SiCl4: a versatile carbene transfer reagent – synthesis from silicochloroform

A new synthetic pathway for the N-heterocyclic carbene adduct (NHCMe)SiCl4 (2) (NHCMe = 1,3-dimethylimidazolidin-2-ylidene) using silicochloroform is presented. Supported by DFT calculations, the energy for dissociation of 2 into the carbene and the SiCl4 fragment was found to be comparable to carbene transfer reagents based on silver(I) chloride. Compound 2 was used to transfer the NHC ligand to three different phosphorus(III) chloro compounds, resulting in the neutral complexes (NHCMe)PCl3 (3a), (NHCMe)PCl2Ph (3b) and (NHCMe)PCl2Me (3c). The sterically non-demanding NHC ligand allowed the phosphorus(III) in complex 3a to be oxidized to phosphorus(V) without loss of the NHC ligand, and afford (NHCMe)PF4H (4). Furthermore, bis-carbene complexes of Ni(II) (5) and Pd(II) (6) were obtained by reacting 2 with the respective metal chlorides.

Photocatalytic Degradation of Organic Pollutants: A Review

Water pollution is increasing at an ever increasing pace and the whole world is in the cancerous grip of this pollution. Various industries are discharging their untreated effluents into the nearby water resources; thus, adding to the existing water pollution to a great extent. Hence, there is a pressing demand to develop an alternate technology for wastewater treatment and in this context; photocatalysis has emerged as an Advanced Oxidation Process with green chemical approach for such a treatment. This chapter deals with photocatalytic degradation of different kinds of organic pollutants; mainly surfactants, pesticides, dyes, phenols, chloro compounds, nitrogen containing compounds etc. Mechanisms of their degradation have also been discussed with hydroxyl and allied radicals as the main active oxidizing species.

Preparation and reactivity of stannyl and germyl complexes of cobalt

Trichlorostannyl complex Co(SnCl3)(CO)2(PPh3)2 (1) was prepared by allowing the chloro compound CoCl(CO)2(PPh3)2 to react with SnCl2·2H2O. Instead, treatment of the iodo complex CoI(CO)2[PPh(OEt)2]2 with SnCl2·2H2O afforded a mixture of Co(SnCl2I)(CO)2[PPh(OEt)2]2 (2a) and Co(SnCl3)(CO)2[PPh(OEt)2]2 (2b) derivatives. Trichlorogermyl complexes Co(GeCl3)(CO)2L2 (3, 4) [L = PPh3, PPh(OEt)2] were prepared by allowing halo compounds CoX(CO)2L2 (X = Cl, I) to react with GeCl2·dioxane. Treatment of trihalostannyl complexes Co(SnCl2X)(CO)2L2 (1, 2) (X = Cl, I) with NaBH4 in ethanol yielded tin trihydrido derivatives Co(SnH3)(CO)2L2 (5, 6). Instead, reaction of Co(SnCl2X)(CO)2[PPh(OEt)2]2 (2) with LiAlH4 in THF yielded the hydrido CoH(CO)2[PPh(OEt)2]2 (7). Trimethylstannyl Co(SnMe3)(CO)2L2 (8, 9) and trialkynylstannyl derivatives Co[Sn(CCPh)3](CO)2L2 (10, 11) were prepared by allowing trihalostannyl compounds Co(SnCl2X)(CO)2L2 (1, 2) to react with MgBrMe and with Li+(PhCC)−, respectively, in THF. The complexes were characterised by spectroscopy (IR and 1H, 31P, 13C, 119Sn NMR) and by X-ray crystal structure determination of Co(SnCl2X)(CO)2[PPh(OEt)2]2 (2) and Co(GeCl3)(CO)2[PPh(OEt)2]2 (4).

Structural differences in eight- and ten-membered heterocyclic tin compounds displaying transannular interactions O⋯Sn: An experimental and theoretical study

Two series of heterocyclic tin compounds of general formula [(S{C6H3(CH2)nS}2O)SnR1R2] with different central ring sizes were prepared. The ten-membered series includes the compounds with n=1 and R1=R2=Ph (5); R1=Cl, R2=Ph (6); R1=Cl, R2=n-Bu (7); R1=R2=Cl (8); the eight-membered series includes the compounds with n=0 and R1=R2=Ph (10); R1=Cl, R2=n-Bu (11) and R1=R2=Cl (12). The compounds 5, 7, 8, 10, and 11 were investigated by single-crystal X-ray diffraction. The chloro compounds 7, 8, and 11 displayed a bipyramidal geometry at the tin atom with different degrees of distortion ranging from 57% to 62%. The diphenyl compounds 5 and 10 displayed a tetrahedral geometry at Sn. The conformation of the central ring in the ten-membered series is similar and is described as boat; the other series displayed two different conformations described as boat–chair and boat–boat. The possible conformers in the gas state of compounds 5, 7, 8, 10, 11, and 12 were investigated by MMFF, LSDA, BLYP, B3LYP, and M06 functionals using the DGDZVP and TZVP basis sets. The structural data of the total optimization agreed with the experimental results. The topological analysis indicated that bond critical points are present along the O⋯Sn direction in the compounds 7, 8, 11, and 12.

Bis(diethylphosphino)methane As a Bridging Ligand in Complexes of Ir2, Rh2, and IrRh: Geminal C–H Activation of α-Olefins

Bis(diethylphosphino)methane (depm, Et2PCH2PEt2) is used as a new bridging ligand for the syntheses of a series of diiridium, dirhodium, and iridium/rhodium complexes, starting from trans-[MM′Cl2(CO)2(depm)2] (M = M′ = Ir (1); M = M′ = Rh (11); M = Ir, M′ = Rh (19)). The reduction of all three chloro compounds in aqueous KOH under an atmosphere of CO produces the neutral tricarbonyl complexes [MM′(CO)3(depm)2] (M = M′ = Ir (2); M = M′ = Rh (12); M = Ir, M′ = Rh (20)). Protonation of these tricarbonyl complexes by triflic acid (HOTf) or Brookhart’s acid (HBArF4) yields the hydride-bridged tricarbonyl complexes [MM′(CO)3(μ-H)(depm)2][X] (M = M′ = Ir (9); M = M′ = Rh (16); M = Ir, M′ = Rh (25); X = SO3CF3 or B(3,5-(CF3)2C6H3)4). Reaction of 2 with methyl triflate yields the methylene/hydride product [Ir2(H)(CO)3(μ-CH2)(depm)2][OTf] (4), while the same reaction with the dirhodium analogue (12) produces the methyl complex [Rh2(CH3)(CO)3(depm)2][OTf] (14) at below −20 °C, which upon warming to above −20 °C results in migratory insertion to yield an acetyl-bridged species, [Rh2(CO)2(μ-C(CH3)O)(depm)2][OTf] (14a). The analogous Rh/Ir species(20) reacts with methyl triflate to give the methyl-tricarbonyl product [IrRh(CH3)(CO)3(depm)2][OTf] (22). Removal of a carbonyl from 4 and 22 yields [MIr(CH3)(CO)2(depm)2][OTf] (M = Ir (5); M = Rh (23)), which are highly susceptible to hydrolysis; however the dirhodium species 14 and 14a are not susceptible to CO loss under the conditions investigated. The reaction of [Ir2(CO)3(μ-H)(depm)2][BArF4] (9) with a number of α-olefins results in double C–H bond activation of the geminal hydrogens to give the vinylidene-bridged trihydride products of the form [Ir2(H)2(CO)2(μ-H)(μ-C═CRR′)(depm)2][BArF4].

Reactivity of an Oxalamide-Based N-Heterocyclic Carbene

The reactivity of the oxalamide-based carbene 2 was investigated. Treatment with styrene or methylacrylate proceeded under carbene addition to yield the respective cyclopropanation products 6a,b. With elemental selenium the selenide 7 was obtained, which was characterized by X-ray diffraction. The Rh complex [(COD)RhCl(2)] (10) was also structurally characterized. From the IR spectrum of the dicarbonyl derivative [(CO)2RhCl(2)] (11) a Tolman electronic parameter of 2068 cm–1 was calculated for the diamidocarbene 2, which characterizes this ligand as the least electron donating NHC known so far. The dimerization product of carbene 2, the intensly fluorescing tetraamido ethylene 3, showed an unexpected chemical stability. Treatment of the chloro compound 1a with methanol afforded the methoxide 5a, whose structure was determined by X-ray diffraction.

Reduction of 4-Chlorophenol by Mg and Mg–Ag Bimetallic Nanocatalysts

Mg nanocatalyst is successfully synthesized in the present study using wet chemical method via the chemical reduction of magnesium sulfate and a reducing agent (sodium borohydride). Size/size distribution characterization is performed by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Subsequently, 4-chlorophenol compound reduction is systematically studied with Mg catalyst. An ultraviolet–visible light (UV–vis) spectrophotometer is used to study the absorption spectra of in situ reduction reaction with time. Gradual disappearance of the peak corresponding to chloro compounds reveals the degradation of chloro compounds with time. Furthermore, the appearance of a new peak reveals the formation of a respective product (phenol). Mg–Ag bimetallic nanocatalyst is also synthesized via an equivalent chemical method and analogous reduction is performed with the catalyst. The performance of the Mg–Ag bimetallic catalyst is compared with that of the Mg nanocatalyst. Superior dechlorination percentage is observed with the Mg–Ag bimetallic nanocatalyst.

Synthesis and reactivity of germyl complexes of manganese and rhenium

Trichlorogermyl complexes M(GeCl 3)(CO) n P 5− n ( 1–4) [M = Mn, Re; n = 2, 3; P = PPh(OEt) 2 ( a), P(OEt) 3 ( b)] were prepared by allowing chloro compounds MCl(CO) n P 5− n to react with an excess of GeCl 2•dioxane in 1,2-dichloroethane. Treatment of compounds 1–4 with LiAlH 4 in thf yielded trihydridegermyl derivatives M(GeH 3)(CO) n P 5− n ( 5–8), whereas treatment of the same complexes with NaBH 4 in ethanol afforded triethoxygermyl derivatives M[Ge(OEt) 3](CO) n P 5− n ( 9–11). Trimethylgermyl compounds M(GeMe 3)(CO) n P 5− n ( 12, 13) and the alkynylgermyl derivative Mn[Ge(C CPh) 3](CO) 3[PPh(OEt) 2] 2 ( 14a) were also prepared by allowing trichlorogermyl compounds 1–4 to react with either MgBrMe or Li +C CPh −, respectively, in thf. Treatment of compound Re(GeCl 3)(CO) 3[PPh(OEt) 2] 2 ( 4a) with SnCl 2•2H 2O gave the stannyl-germyl derivative Re[GeCl 2(SnCl 3)](CO) 3[PPh(OEt) 2] 2 ( 15a). The complexes were characterised by spectroscopy and X-ray crystal structure determination of 4a, 5a, and 13a.

Further studies on the dialkylation chemistry of [Pt2(μ-S)2(PPh3)4] with activated alkyl halides RC(O)CH2X (X = Cl, Br)

Further studies have been carried out into the reactivity of [Pt2(μ-S)2(PPh3)4] towards a range of activated alkylating agents of the type RC(O)CH2X (R=organic moiety, e.g. phenyl, pyrenyl; X=Cl, Br). Alkylation of both sulfide centers is observed for PhC(O)CH2Br, 3-(bromoacetyl)coumarin [CouC(O)CH2Br], and 1-(bromoacetyl)pyrene [PyrC(O)CH2Br], giving dications [Pt2{μ-SCH2C(O)R}2(PPh3)4]2+, isolated as their PF6− salts. The X-ray structure of [Pt2{μ-SCH2C(O)Ph}2(PPh3)4](PF6)2 shows the presence of short Pt⋯O contacts. In contrast, the corresponding chloro compounds [typified by PhC(O)CH2Cl] and imino analogues [e.g. PhC(NOH)CH2Br] do not dialkylate [Pt2(μ-S)2(PPh3)4]. The ability of PhC(O)CH2Br to dialkylate [Pt2(μ-S)2(PPh3)4] allows the synthesis of new mixed-alkyl dithiolate derivatives of the type [Pt2{μ-SCH2C(O)Ph}(μ-SR)(PPh3)4]2+ (R=Et or n-Bu), through alkylation of in situ-generated monoalkylated compounds [Pt2(μ-S)(μ-SR)(PPh3)4]+ (from [Pt2(μ-S)2(PPh3)4] and excess RBr). In these heterodialkylated systems ligand replacement of PPh3 occurs by the bromide ions in the reaction mixture forming monocations [Pt2{μ-SCH2C(O)Ph}(μ-SR)(PPh3)3Br]+. This ligand substitution can be easily suppressed by addition of PPh3 to the reaction mixture. The complex [Pt2{μ-SCH2C(O)Ph}(μ-SBu)(PPh3)4]2+ was crystallographically characterized. X-ray crystal structures of the bromide-containing complexes [Pt2{μ-SCH2C(O)Ph}(μ-SR)(PPh3)3Br]+ (R=Et, Bu) are also reported. In both structures the coordinated bromide is trans to the SCH2C(O)Ph ligand, which adopts an axial position, while the ethyl and butyl substituents adopt equatorial positions, in contrast to the structures of the dialkylated complexes [Pt2{μ-SCH2C(O)Ph}2(PPh3)4]2+ and [Pt2{μ-SCH2C(O)Ph}(μ-SBu)(PPh3)4]2+ (and many other known analogues) where both alkyl groups adopt axial positions.

C-C (alkynylation) vs C-O (ether) bond formation under Pd/C-Cu catalysis: synthesis and pharmacological evaluation of 4-alkynylthieno[2,3-d]pyrimidines.

The Pd/C–CuI–PPh3 catalytic system facilitated C–C bond formation between 4-chlorothieno[2,3-d]pyrimidines and terminal alkynes in methanol with high selectivity without generating any significant side products arising from C–O bond formation between the chloro compounds and methanol. A variety of novel 4-alkynylthieno[2,3- d]pyrimidines were prepared via alkynylation of 4-chlorothieno[2,3-d]pyrimidines in good to excellent yields. Some of the compounds synthesized were tested for cytotoxic activity in vitro.

Electroreduction of Organic Compounds, 37 [1]. Electroreduction of 1,4-Dichlorobicyclo[2.2.2]octane-2-carboxamides

Several 1,4-dichlorobicyclo[2.2.2]octanecarboxamides were prepared, which were expected to be suitable precursors for the electrochemical synthesis of [2.2.2]propellanes. Their potentiostatic electroreduction at extremely negative potentials in THF, however, did not lead to the expected [2.2.2]propellanes. Instead, protio-dechlorination to form the corresponding bicyclo[2.2.2]octanecarboxamides occurred, even under rigorous exclusion of moisture and oxygen. Ring-opened olefins were produced as by-products. Polytetrahydrofuran was formed when the supporting electrolyte tetrabutylammonium hexafluorophosphate was electrolyzed at −3.5 V in the absence of an organic chloro compound as depolarizer. The experimental results are interpreted in terms of semi-empirical MO calculations.

Reaction of chloropyridazin-3(2H)-ones with iodide. Part II.

The reactions of 5-chloro-6-phenyl-,4,5-dichloro-6-phenyl- and 5-chloro-6-(2,4-dichlorophenyl)2-methylpyridazin-3(2H)-ones with 57% aqueous hydrogen iodide or sodium iodide in dimethyl formamide, respectively, are described. Upon treatment of chloro compounds with 57% hydrogen iodide, besides nucleophilic substitution of chloro- by iodo substituent, subsequent hydrodeiodination also occurred. Thus, e.g. 4,5-dichloro-2-methyl-6-phenylpyridazin-3(2H)-one gave first 5-chloro-4-iodo-2-methyl-6-phenylpyridazin-3(2H)-one and in the next step, 5-chloro2-methyl-6-phenylpyridazin-3(2H)-one. Similarly, treatment of 5-chloro-2-methyl-6phenylpyridazin-3(2H)-one led to the formation of 5-iodo-2-methyl-6-phenylpyridazin-3(2H)one and 2-methyl-6-phenylpyridazin-3(2H)-one. The structure of each new product was proved by 1 H, 13 C and partly by 15 N NMR spectroscopy.

ChemInform Abstract: Synthesis of Some Thiazolo(5,4-d)pyrimidines.

Abstract 4-Amino-3-phenyl-2-thioxothiazol-5-carboxamide (1) reacts with aromatic aldehydes to form thiazolo-pyrimidines (2a,b ), and with acetic anhydride to thiazolopyrimidine (2C ). Thiazolocarboxamides (1a,b ) were converted to thiazolotriazines (3a,b ) by reaction with nitrous acid. When thiazolopyrimidine (2C ) was refluxed with POCl3, the corresponding chlorothiazolopyrimidine (4) was isolated. The produced chloro compound (4) can be converted into the corresponding thiazolopyrimidindithiones (5) or substituted aminothiazolopyrimidines (6,7), when allowed to react either with thiourea, aromatic amine or hydrazine hydrate. S-alkylated thiazolopyrimidines (8a-k ) were produced when compound (5) was reacted with halo compounds or acrylonitrile. Hydrazino compound (7) reacts with acetylacetone to produce the pyrazolylthiazolopyrimidine (9).

ChemInform Abstract: Synthesis of Bis[1,2]dithiolo[1,4]thiazines and a [1,2]Dithiolo[1,4]thiazine from Tertiary Diisopropylamines.

The reaction of N-(2-chloroethyl)diisopropylamine 1a with S2Cl2 allows the selective one-pot preparation of the tricyclic 4-(2-chloroethyl) bisdithiolothiazines 2-4 or, by addition of phosphorus pentasulfide at a late stage in the reaction, of the dithiolothiazine 5. The chloroethyl derivative 2 is also obtained from (2-diisopropylamino)ethanethiol 1b, or its disulfide 1c, with S2Cl2, in a rare conversion of a thiol or disulfide into the corresponding chloro compound. Compounds 2 and 5 are also obtained from N- (2-hydroxyethyl)diisopropylamine 1d, though in much lower yields. The reaction of N-(2-phenylthioethyl) (1e) or N-(2- phthalimidoethyl)diisopropylamines 1f,g affords bisdithiolothiazines 7, 8, 9, and 11 and the dithiolopyrrole 10. A coherent set of reaction pathways for the formation of these products is proposed. X-ray crystallography shows that the bisdithiolothiazine ring system of 2 is folded out of planarity about the thiazine N-S vector, with the N-chloroethyl group folded back over the thiazine ring with the chlorine atom lying above the thiazine sulfur atom; the dithiolothiazine ring system of 5 has the thiazine ring in a 'sofa' conformation.